VOLUNTARY ANNOUNCEMENT - CLINICAL DATA OF ALMB-0168 FOR THE TREATMENT OF OSTEOSARCOMA TO BE PRESENTED AT THE 2023 ASCO ANNUAL MEETING

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement, make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement. (Incorpor ated in H ong Kong with limi ted liabi lity) (Stock co de: 1093) VOLUNTARY ANNOUNCEMENT CLINICAL DATA OF ALMB-0168 FOR THE TREATMENT OF OSTEOSARCOMA TO BE PRESENTED AT THE 2023 ASCO ANNUAL MEETING The board of directors (the “Board”) of CSPC Pharmaceutical Group Limited (the “Company”, togetherwithitssubsidiaries, the“Group”)ispleasedtoannouncethatAlaMabTherapeutics Inc.,a subsidiary oftheCompany, willpresent thepreliminary positive results onefficacy andsafety ofa Phase I clinical trial of ALMB-0168 in patients with osteosarcoma at the upcoming 2023 ASCO annual meeting taking place on 2-6 June 2023, titled “ALMB-0168, a novel Cx43 hemichannel agonist monoclonal antibody, for metastatic or unresectable osteosarcoma after standard chemotherapy: Amulticenter, open-label, single-arm, phase Istudy”. Osteosarcoma isthemostcommon primary malignant bonetumor which affects mostly adolescents (under 20 years old). However, the treatment of metastatic or unresectable osteosarcoma after standard chemotherapy remains a significant clinical challenge. ALMB-0168 is a first-in-class antibody agonist for novel drug target connexin 43 (Cx43) hemichannels and has been shown to suppress thegrowthandmigration ofosteosarcoma andbreastcancerbonemetastases inpreclinical studies. ALMB-0168 has also been granted Orphan Drug Designation (ODD) and Rare Pediatric DiseaseDesignation(RPD)bytheU.S.FoodandDrugAdministration fortreatmentofosteosarcoma. The study is a multicenter, open-label, single-arm Phase 1 clinical trial to evaluate the safety, tolerability,andpreliminaryefficacyofALMB-0168fortreatmentofosteosarcoma.Thetrialenrolled patients of ≥16 years with histologically confirmed osteosarcoma who progressed after standard chemotherapy. -1- Atotalof13patientswereevaluableforresponse.Theoverallresponserate(ORR)was15.4%(2/13, 95%CI:1.9-45.5%), including 2partialresponses (PR),1patienteachat6mg/kgand18mg/kg.The patientat6mg/kg,whohad≥3priorlinesoftherapyandlungmetastases, achieved durabledisease controlwithstabledisease(SD)for33weeksfollowedbyPRfor8+weeks(atthetimeofanalysis). Thedisease control rate(DCR)was53.8%(7/13, 95%CI:25.1-80.8%) with2PRsand5SDs.No dose-limiting toxicities, Cx43-related cardiac events orsevere hepatic events wereobserved. Inconclusion, ALMB-0168 demonstrated encouraging efficacy andtolerable safety inpatients with metastatic orunresectable osteosarcoma after standard chemotherapy inthe Phase Idose-escalation trial. ByOrder oftheBoard CSPC Pharmaceutical Group Limited CAI Dongchen Chairman HongKong, 30May2023 As at the date of this announcement, the Board comprises Mr. CAI Dongchen, Mr. ZHANG Cuilong, Mr. WANG Zhenguo, Mr. PAN Weidong, Mr. WANG Huaiyu, Dr. LI Chunlei, Dr. WANG Qingxi, Mr. CHAK Kin Man and Dr. JIANG Hao as executive directors; and Mr. WANG Bo, Mr. CHEN Chuan, Prof. WANG Hongguang, Mr. AU Chun Kwok Alan, Mr. LAW Cheuk Kin Stephen and Ms. LI Quan as independent non-executive directors. -2-

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